Caister Academic Press

Zika virus spread

Zika virus has been known to circulate in parts of sub-Saharan Africa for many years since its first isolation in Uganda in 1947-48, and it probably spread to south-east Asia in about 1945-50. Two major lineages then evolved, one in Africa and one in Asia, where it caused a relatively minor disease of fever with a rash and arthralgia. The virus spread from Asia to Yap in 2007 causing the largest known outbreak of human disease, and from Asia to the South Pacific in 2013-14, including French Polynesia where it caused an explosive outbreak with over 28,000 cases, and subsequently spread to Cook Islands, Easter Island, and New Caledonia. Phylogenetic studies using isolates obtained from both outbreaks, Yap and the South Pacific, found that the outbreaks were caused by closely related viruses belonging to the Asian lineage. Viruses circulating in Africa indicated that the African lineage comprises two tightly bound clades, one containing isolates from Nigeria and Senegal, and the other comprising isolates from Uganda, Senegal and Central African Republic, but both clades contained viruses from Cote d'Ivoire, and there was evidence consistent with at least two introductions into West Africa.

From Hall et al. in Arboviruses: Molecular Biology, Evolution and Control (Chapter 10)